Devices for treating femur fractures are known. See, for example, EP-A2 0 347 874, which has a conventional sleeve strap and a trochanter stabilization plate that can be separably connected with the sleeve strap. However, a disadvantage of this device is its interlocking construction, which makes it necessary to attach the trochanter stabilization plate directly to the bone and to attach the sleeve strap over the trochanter stabilization plate, resting on the bone. In this obligatory sequence of the two components, the surgeon must make a decision right at the start whether or not to use a trochanter stabilization plate. Later installation of a trochanter stabilization plate, after a bone break has been treated with a sleeve strap, is no longer possible without completely removing the sleeve strap. In hospital practice it is desirable that the decision on whether or not to use a trochanter stabilization plate be made as late as possible.